Spurred by recent observations of 24 μm emission within wind-blown
bubbles (WBBs), we study the role that dust can play in such
environments and build an approximate model of a particular WBB, "N49."
First, we model the observations with a dusty WBB, and then ask whether
dust could survive within N49 to its present age (estimated to be 5
× 105 to 106 yr). We find that dust
sputtering and especially dust-gas friction would imply relatively short
timescales (t ~ 104 yr) for dust survival in the wind-shocked
region of the bubble. To explain the 24 μm emission, we postulate
that the grains are replenished within the WBB by destruction of
embedded, dense cloudlets of interstellar medium gas that have been
overrun by the expanding WBB. We calculate the ablation timescales for
cloudlets within N49 and find approximate parameters for the embedded
cloudlets that can replenish the dust; the parameters for the cloudlets
are roughly similar to those observed in other nebula. Such dust will
have an important effect on the bubble: including simple dust cooling in
a WBB model for N49, we find that the luminosity is higher by
approximately a factor of 6 at a bubble age of about 104 yr.
At ages of 107 yr, the energy contained in the bubble is
lower by about a factor of 8 if dust is included; if dust must be
replenished within the bubble, the associated accompanying gas mass will
also be very important to WBB cooling and evolution. While more detailed
models are certainly called for, this work illustrates the possible
strong importance of dust in WBBs, and is a first step toward models of
dusty WBBs.